1. Field of the Invention
The present invention relates to the packaging of integrated circuits and, more particularly, to an attachment of a heat spreader to an integrated circuit package.
2. Description of Related Art
A top view of a conventional heat spreader-package assembly 10 is shown in FIG. 1. The conventional heat spreader 11 has a substantially square upper portion 12 with sidewalls 14 extending from the edges of the upper portion 12. A flange 16 extends from the sidewalls 14 and is substantially parallel to an upper portion 12 of the package.
A side sectional view of the conventional heat spreader-package assembly 10 is shown in FIG. 2. The assembly includes package board 18 having an integrated circuit die 20 mounted thereto. The heat spreader 11 is mounted to the package board 18 and serves both to protect physically the integrated circuit die 20 and spread the heat generated by the die 20. An adhesive 22 is placed between the flange 16 and the upper surface of the package board 18 to hold the heat spreader 11 in place.
There are problems, however, with conventional heat spreader-package assemblies. For example, as shown in FIG. 2, the adhesive contacts only the upper surface of the package board and the underside of the flange. That is, there is no force that will act against the upper surface of the flange to hold the flange against the package board to resist upward forces on the spreader 11. Thus, the connection between the heat spreader and the package is somewhat weaker than may be desirable.
There is a need for a heat spreader having a stronger connection between the heat spreader and the package board. More specifically, there is a need for a heat spreader-package assembly in which an adhesive acts on an upper side of the flange to hold the heat spreader firmly in place.
These and other needs are met by embodiments of the present invention which provides a heat spreader having an upper portion; a plurality of sidewalls extending from the upper portion; and a flange extending from the sidewalls and having a plurality of holes adapted to allow an adhesive to flow therethrough to establish a riveted connection between the heat spreader and an integrated circuit package.
One advantage of such a heat spreader is that the adhesive, after it has flowed through the holes cured, forms a riveted connection between the heat spreader and the integrated circuit package board. Thus, a force acts on the upper surface of the flange to hold the heat spreader more firmly in place.
The earlier stated needs are also met by another embodiment of the present invention which provides a method of attaching a heat spreader to a package of a semiconductor device, comprising forming holes in a flange of the heat spreader; placing an adhesive on an upper surface of the package; bringing the flange of the heat spreader into contact with the adhesive; allowing the adhesive to partially flow through the holes; and curing the adhesive to establish a riveted connection between the heat spreader and the package.
Additional advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.